Friday, May 11, 2007

Another Viewpoint: Fiber Folly Finally Fizzled

I enjoy hearing different opinions as it relates to health. Although I'm no expert in this field of study, I have learned more about diet, health, and nutrition over the past few years than I have anything else in my entire life (even more so than all those years of college and graduate school studying English and Public Policy!).

I am a fan of people consuming adequate amounts of fiber, but it really should be the right kinds of fiber as you will learn from this column submitted by one of my readers today which was taken directly from the writings of Dr. Barry Groves, a brilliant UK researcher who shares his professional and thorough findings about the low-carb lifestyle at the fantastic web site located at http://www.second-opinions.co.uk. (PLEASE REFERENCE THIS SOURCE FOR MORE EXTENSIVE NUTRITIONAL INFORMATION).

While I have always been a strong supporter of fiber intake, this essay may make you stop and think about the source of your fiber. Let me know what you think about this and feel free to debate the assertions Dr. Groves makes.

Here's the piece entitled "Fiber Folly Finally Fizzled":

Little known fact: The wrong type(s) and quantities of fiber may cause cancers and impairs and even prohibits the absorption of important nutrients and minerals. So much for the myth that vegetarians have “the benefit” of four to six bowel movements a day...

We are all throughly familiar with the importance of sufficient fiber in the diet; in fact we hear and see it everywhere. Even specialty products, like “All-Bran” and other engineered-non foods as well as fiber supplements are marketed prominently, supposedly providing the all-important additional fiber in the diet. Even we, low-carbers, are familiar with subtracting fiber from the carbohydrate count of foods.

Indeed the intake of specific types of fiber can have metabolic advantages, but very few know that it is important to keep in mind what type and quality of fiber is ingested and especially in what quantities. Not many people--and even fewer health care professionals, whom should know better--are aware that an excess of fiber can be very unhealthy.

Fiber, it is said, is necessary to promote regularity, and also protects us from all kinds of nasty diseases, especially intestinal disorders and diseases like cancer. Especially the media has picked up on this story and is keen to repeat this message ad nauseum.

However, as so often is the case, science tells us a different story.

There is currently growing skepticism that lack of fiber causes cancer; some studies even suggesting that a fiber-enhanced diet increases the risk of colon cancer.

The original prevailing “fiber-is-a-panacea-theory” is based on observations of a certain Dr. Dennis Burkitt. He observed that relatively few rural black Africans suffer from cancer of the colon. He attributed this to their relatively crude diet.

The theory was that, as fiber made food travel through the gut faster, it allowed less time for cancer-inducing agents to form. Remember that this argument is often cited for us low-carbers, as we are supposed (according to “common wisdom”) to consume tons of meat daily, which digests slower than, for example, vegetables. This, of course, presupposes that food becomes carcinogenic in the gut and, “unfortunately”, there was no evidence that it did. Neither was there any evidence that moving food through the intestine at a faster rate decreased the risk of colon cancer.

Moreover, the rural Africans' lifestyle was far from that of the Western city dweller: their diet is different, but also they were not exposed to so many pollutants, toxins or mental stresses. Indeed, there were many factors that could have been responsible for a difference in disease patterns. Other communities - the Mormons of Utah, for example - also enjoyed a low incidence of colon cancer yet they ate a low-fiber diet.

So the theory was, in fact, completely unsubstantiated and it was indeed later to be disproved as the rural Africans moved into towns and adopted a Western style “low fiber” diet. Their incidence of colon cancer has remained low and this has continued with the second generation. Nevertheless, these later findings were not publicized by the media.

Of course, the Food Companies and Pharmaceuticals quickly picked up on the media hype and were quick to see the potential in the recommendation. Burkitt's recommendation was based on vegetable fiber, but bran (cereal fiber) has a far higher fiber content and bran was a practically worthless by-product of the milling process that, until then, had been discarded as worthless. Suddenly however it became a highly priced profit maker.

Although totally inedible, backed by Burkitt's fiber hypothesis, bran could now be promoted as a valuable food. Although even Burkitts own coresearchers and partners warned publicly that Africans (on which the theory was based) do not consume bran or cereals, to momentum was already unstoppable.

And thus the fiber-theory was born.

Fiber and coronary heart diseaseThe idea that fiber could protect against heart attacks was hypothesized by Trowell in 1972, again based on research on rural Africans. The dietary intervention trials conducted, however, concluded that increasing dietary fiber had no beneficial effect on heart disease. Later research again confirmed these findings.

Fiber and other diseasesIt is also interesting to consider the claims for fiber in curing or preventing other diseases. For example, bran has been a popular way to manage irritable bowel syndrome (IBS) for about thirty years, despite the fact that no placebo-controlled study of bran in IBS has yet shown any convincing beneficial effect. A study, published in 1994, found that while fruit fiber was effective, bran only made the situation worse. Far from being a cure for IBS, the researchers found that it was the bran that was causing it! Bran also caused bowel disturbances, abdominal distension and pain.

Moreover, there is no direct evidence that an increase of fiber by itself will prevent or cure the other diseases. With respect to colon cancer, Burkitt's theory was questioned with the suggestion that the low cancer rates in rural Africans may be due to their high early death rates from other causes, so that they do not reach the age at which cancer peaks in Europeans. As the Africans' life expectancy was only forty years at the time Burkitt did his research and Western cancers don't peak until the age of sixty-five, one wonders why this wasn't noticed before.

Other adverse effectsTests into the supposed benefits of dietary fiber soon showed that there could be other harmful side effects. All the nutrients in food are absorbed through the gut wall and this takes time. Fiber, by speeding food through the gut faster so that less nutrients are absorbed, inhibits the absorption of iron, calcium, phosphorus, magnesium, energy, proteins, fats and vitamins A, D, E and K. This happens with all types of fiber although with a normal Western-style, nutrient-rich diet, the loss caused by vegetable fiber intake is unimportant.

More importantly, however, phytate found in cereal fiber (or bran) also binds with calcium, iron and zinc making them indigestible, which in turn causes impaired- or even no absorption. One study, for example, showed that subjects absorbed more iron from white bread than from wholemeal bread even though their intakes of iron were fifty percent higher with the wholemeal bread! Bran has also been shown to cause faecal losses of calcium, iron, zinc, phosphorus, nitrogen, fats, fatty acids and sterols, thus depleting the body of these materials and creating deficiencies.

These findings are a cause for concern in several sections of the population who are at considerable risk from eating too much fiber - and bran fiber in particular:

1. The incidence of osteoporosis (brittle bone disease) is increasing and now affects one in two post-menopausal women, one in five of whom will die as a direct result. Osteoporosis is also increasingly affecting men. Osteoporosis is caused by several factors, but lack of calcium is the basic problem. Bran both inhibits the absorption of calcium from food and depletes the body of the calcium it has. Moreover, zinc, which bones need to heal, is another mineral whose absorption is adversely affected by bran.

2. Sufferers from Alzheimer's Disease (senile dementia) are found to have abnormal amounts of aluminium in their brains. Tests on the people of Guam and parts of New Guinea and Japan, who get Alzheimer's disease at a much younger age, suggest that it is lack of calcium, causing a hormonal imbalance that permits the aluminium to penetrate the brain.

3. Infants may suffer similar brain damage if fed soy-based baby milk as this too has a high phytate content, inhibiting the absorption of zinc, which is essential for proper brain development.

4. Vitamin deficiency diseases such as rickets that were common in Britain until a diet high in dairy products and meat was advocated are on the increase again. The situation is getting so bad here that doctors suggest that vegetarian-based fad diets should be classified a form of child abuse.

5. In the UK, USA, Canada and South Africa the intake of 'anti-nutrients' such as dietary fiber that impair the absorption of iron, accompanied by a low intake of meat (another result of the diet-heart recommendations), is producing a real risk of iron deficiency anaemia.

6. Depression, anorexia, low birth weight, slow growth, mental retardation , and amenorrhoea are associated with deficiencies of zinc and the first five of these are also associated with a deficiency of iron.

Because of the phytate, Professor David Southgate, arguably the world's leading authority on the effects of fiber, concludes that infants, children, young adolescents and pregnant women whose mineral needs are greater should be protected from excessive consumption of fiber.

Writing of the colon cancer risk, Drs. H. S. Wasan and R. A. Goodlad of the Imperial Cancer Research Fund stated in 1996: "Until individual constituents of fiber have been shown to have, at the very least, a non-detrimental effect in prospective human trials, we urge that restraint should be shown in adding fiber supplements to foods, and that unsubstantiated health claims be restricted." . . . "Specific dietary fiber supplements, embraced as nutriceuticals or functional foods, are an unknown and potentially damaging way to influence modern dietary habits of the general population."

Until fiber can be shown not to be detrimental they suggest that "restraint should be shown in adding fiber supplements to foods, and that unsubstantiated health claims should be restricted".

Confirmed By Large-Scale TrialsJanuary 1999 saw the publication of the largest trial into the effects on fiber on colon cancer ever conducted. After studying 88,757 women for sixteen years, doctors at the Brigham and Women's Hospital and Harvard Medical School say that "No significant association between fiber intake and the risk of colorectal adenoma was found." . . . "Our data do not support the existence of an important protective effect of dietary fiber against colorectal cancer or adenoma."

Conclusions(Selected) vegetable and fruit fibers may promote regularity and have the added benefit of lowering the glycemic impact of foods, but few other advantages have been scientifically proven. The quality of the fibers ingested, and especially the quantity are important. Too much fiber may very well not be a good thing, as it has been shown to impair and even prohibit absorption of essential nutrients. Especially cereal fibers, or bran, are really bad news. The usual bran that is pushed at us - wheat bran- should be avoided completely.

4 Comments:

This was a nice article Jimmy. It really seems to kind of glaringly lack one thing, though: an example list of foods for good fiber vs. foods for bad fiber. Aside from the generality of 'fruit vs. bran' -- is that wheat? Only wheat? -- there isn't really any info about "how to make a better choice".

Thanks for posting this. I've come to the conclusion that fiber is overrated. It's supposed to help fill you up and even prevent diabetes. However, I used to eat plenty of whole grain fiber. BUT -- it didn't curb my cravings, didn't help me attain or maintain a healthy body weight, and didn't help me avoid diabetes. It only kept me regular.

You're better off to get most of your fiber from non-starchy veggies and low sugar fruits and very little from grains. This article hits it on the head. Funny thing, despite all the hype about whole grains, I am getting better since I've cut way back on grains.

Just to push the envelope a bit more - fiber may contribute to colon cancer. Fiber is not digested by us and passes into the ileum/colon where it is digested by bacteria. One of the by-products of digestion is butyrate - a short chain fatty acid that has many effects on the digestive tract. One effect is the suppression of the immune response in areas where it is produced in large amounts. See http://www.fasebj.org/cgi/content/full/14/15/2380 for some of the effects. When we consume large amounts of carbohydrates or fiber, the bacterial production of butyrate is maintained. A long term suppression of our immune system in the lining of the colon would look like a recipe for allowing cancers to proliferate to me.